Sucker rod



- Dec. 30, 1969 I R w. HARRISON SUCKER ROD,

Filed May 15; 1968 Arr RNEVJ United States Patent 3,486,557 SUCKER ROD Robert W. Harrison, 710 W. Creekside Drive, Houston, Tex. 77024 Filed May 15, 1968, Ser. No. 729,254 Int. Cl. E21b 17/00; E04c 3/30; B21d 39/04 U.S. Cl. 166-68 3 Claims ABSTRACT OF THE DISCLOSURE The present invention involves sucker rods to be used in pumping wells such as oil wells, gas wells and the like. The sucker rod described herein is comprised of a rod made of a suitable substance such as plastics, fiber glass, steel or the like, molded or cast about a cable of substantially the same length as the rod. The cable is secured throughout its length to the rod, and if desired, its ends may be made even more secure, as for example, extending them into recesses and filling the recesses with molten metal.

BACKGROUND OF THE INVENTION The present invention relates to sucker rods used in pumping wells, and more particularly, to an improved design in sucker rods which incorporates a length of cable throughout the center of the rod. By securing the cable length at opposite ends of the rod, means are still available to pull the pumping apparatus from the Well should the rod break.

Sucker rods are used in such as producing oil wells to connect the pumping unit on the surface with the downhole pump. Since the downhole pump utilizes a reciprocating plunger to pump oil to the surface, the sucker rods must be fairly rigid to move the pump plunger in its downward stroke.

Furthermore, substantial strength is required in the rod, especially during the upstroke of the pumping unit. This latter requirement is due to the fact that the individual rods must lift the weight of the rod string and the column of liquid being pumped, as Well as the reciprocating plunger.

These relatively rigid sucker rods are somewhat susceptible to breakage due to their rigidity and to the large compression and tension forces alternately placed on the rods. Furthermore, acidic conditions can sometimes exist in producing wells, especially where certain highly corrosive oils are being pumped, or salt water or sulfur water is present in the well. These conditions can bring about corrosion of the rod with resultant failure thereof.

The primary problem, however, is the stress placed on the individual rods and the rod string by the reciprocating movement thereof. The constant change from compression to tension places a great strain on the rods. This added to the previously mentioned corrosive effect, as well as wear caused by friction between rods and tubing, result in the not uncommon occurrence of a sucker rod breaking. Such a break occurs often as a result of crystallization in prior art metal rods, especially in the portion of the rods known as the shank.

When there is a break in a sucker rod, the pumping apparatus below the break is, of course, disconnected from the equipment at the surface and cannot be pulled from the Well. It then becomes necessary to fish this portion of the pumping apparatus from the well. As will be readily understood, these fishing operations are quite expensive and time consuming. The expense is increased substantially when one considers that production from the well is stopped while the fishing operations take place.

SUMMARY OF THE INVENTION By use of the present invention, however, even should Patented Dec. 30, 1969 the sucker rod break, a cable which extends throughout the length of the rod will still remain intact. This cable is of a strength sufficient to hold the weight of the pumping apparatus extending below it. Accordingly, when such a break occurs, the operators can still remove the pumping apparatus below the rod where the break has occurred. It is then but a simple matterto remove the broken rod and replace it with another rod.

As an additional feature, the preferred embodiment of the rods of the present invention are constructed from a light material such as plastics or fiber glass. The use of these materials will decrease the weight of the sucker rod by a substantial amount, and as a result, will decrease the stress placed on the rods and couplings. Furthermore, these materials can better resist the previously mentioned corrosive effects when present. Adequate strength can be provided in both the rod itself and the coupling means used with the rod. Additional security and strength is provided by the use of the cable, which extends throughout the length of the rod.

It is, of course, necessary that the cable be fastened securely to the sucker rod. This will insure the holding together of the two parts of the broken rod by the cable regardless of where the break occurs. This, of course, is with the exception of certain breaks that may occur at a joint of coupling.

It is, therefore, an object of the present invention to provide an improved sucker rod to insure against the loss of equipment due to breakage of such rods and the substantial loss of time and money in recovering such equipment.

A further object of the present invention is to provide such an improved rod having as an integral part thereof a cable about which the rod is formed, which cable will remain intact should the rod break, thereby providing means by which the pumping equipment may be readily recovered from the well.

Yet another object is to provide a lighter sucker rod string comprised of a sucker rod made primarily from a material such as plastic or fiber glass, and having extending therethrough and fixedly secured thereto a centrally disposed cable.

Still another object of the present invention is to provide such a rod having the ends of the longitudinally disposed cable secured at their respective ends of the rod so as to protect against breakage occurring at any point throughout the length of the rod.

Another object is to provide such an improved sucker rod made of a corrosive resistant material.

Yet another object of the present invention is to provide I a method of making such an improved sucker rod.

Other and further objects, features and advantages will be apparent from an examination of the following descriptions of presently preferred embodiments of this invention, which are given for the purpose of disclosure, when taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING 3 DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to FIGURE 1, a production well, generally indicated by the numeral 10 utilizes a pumping unit 12 on the surface. The actual well itself is defined by a casing 14 which extends the length of the well. Near the production level or formation 16 of the well, a cement casing 18 may be positioned to co-act with a packer 20. Positioned within the casing 14 is the tubing 22. Openings 24 are located in the tubing 22 to allow the oil and gas to flow into the tubing from the producing formation 16.

The downhole pumping apparatus is comprised of a suction pipe 26, having a ball valve indicated at 28. A pump plunger 30 is mounted within the tubing and above the ball valve 28 for reciprocating movement produced by the pumping unit 12. A traveling ball valve 32 is located within the plunger. The well is capped as at 34 having a first outlet 36 for the oil and gas that is pumped up through the tubing, and a second outlet 38 for gas which rises naturally to the surface.

The pump plunger 30 is connected to the surface pumping unit 12 by means of a sucker rod string 40, which is only schematically shown in FIGURE 1. The reciprocating motion generated by the main pumping unit 12 is transmitted by means of these sucker rods to the pump plunger.

The apparatus shown in FIGURE 1 is quite well known in the art, and its operation is understood by those skilled in the pumping art. For this reason, no lengthy explanation as to its operation need be given. Generally, however, the pumping unit has a motor driven rocker arm and head which rocks back and forth, thus imparting reciprocal motion to the rod string 40 and to the pump plunger 30. As the plunger moves up, it sucks the oil and/or gas from the producing formation. During its downstroke, the ball valve 28 acts to prevent the production drawn above the suction pipe 26 from returning to the lower portion of the well. Additional upstrokes by the plunger will eventually lift the production out the well at the surface.

Turning now to FIGURE 2, the sucker rod 41 which is the subject of the present invention will now be described. This rod is comprised generally of a fiber glass body 42 which has wrench flats 44 and threads 46 on both ends of the rod 40. The wrench flats 44 are used to receive the appropriate tool to tighten the rods to adjacent rods or other pumping equipment by means of the threaded portion of pin 46 being threadedly received by a coupling or box 47 which is threadingly engaged to the adjacent rod or other equipment. A cable 48 extends through the center of the rod 40 along its longitudinal axis.

Recesses 50 are located at opposite ends of the rod in this particular embodiment, only one being shown in FIGURE 2 for the purpose of simplicity. It is understood, however, that the recess at the opposite end is constructed and functions the same as the one shown. The end 52 of the cable 48 extends into the recess and is there splayed. Molten metal is then poured into the recess 50 and allowed to harden about the splayed end 52 of the cable 48. The splayed end of the cable should extend to the end of the rod 41 to give the added protection provided by the cable should a break occur in the upper part of the pin 46.

Turning now to the operation of the sucker rod 41, it is attached into the rod string as previously described. Since the pump plunger 30 must be forced downward through the production that it has sucked past valve 28, it is necessary that the sucker rod string have a certain amount of rigidity for this purpose. Such rigidity is provided in the present invention by the fiber glass casing 42. Due to this rigidity, however, this casing 42 is susceptible to breakage. Sucker rods are the most susceptible to this breakage at their shank portions S.

Should such a break occur, as at 56, producing the two sections A and B of the rod, the cable 48 will remain intact as shown in FIGURE 2. Due to the inherent flexible nature of the cable, the possibility of breakage in the cable at the same time that the rod breaks is quite small. As one will readily understand, since the cable 48 is secured to the rod throughout its length, as well as in the recesses 50, the two sections of the rod will be held together. The cable 48 is selected to have suflicient strength to support the remainder of the pumping apparatus which, should a break occur, depends from the cable. Accordingly, as soon as such a break occurs and is realized, the rod string may be pulled up until the broken rod is reached. This rod may then be replaced, and the string returned to its pumping position.

It is, of course, impossible to predict where the rod 40 will break, although the great majority of breaks occur at the shank S. Due to the unpredictability of these breaks, it is essential that the cable 48 be secured throughout the length of the rod 41. If the cable is secured in this manner, the two sections A and B will be supported, regardless of where the break occurs. This would not be true, however, should the break occur in the coupling or box 47 between the individual sucker rods, due to the fact that the cables 48 extend throughout the length of each individual rod and do not extend between rods or throughout the length of the rod string. A break in the portion of the box 47 connected to the pin, however, would still be supported by the cable if enough of the box above the break (or in segment A of the string) was in threaded engagement with the pin of the rod extending below the break (or in segment B of the string).

In the embodiment of FIGURE 2, the end 52 was splayed within the recess 50 and Babbitt metal poured into the recess. This formed a very secure fastening means for the cable ends, thus insuring the proper operation of the cable reenforcing regardless of where a break occurs. The ends 52 of the cable should extend to the outermost ends of the recesses to guard against breaks in either the pin 46 or box 47 as much as possible.

In FIGURE 3, another manner of attaching the cable ends is shown. Here the end 52 of the cable 48 is simply cut off flush with the end of the rod 41. As with the last embodiment, the cable is made fast to the rod throughout its length, and therefore, the recesses 50 filled with Babbitt are not necessary. In fact, the embodiment of FIGURE 3 is the preferable one due to its simplicity and ease of manufacturing. Since it also extends to the very end of the rod 41 and is attached throughout its length, the embodiment of FIGURE 3 protects against breaks in the pin 46 or the box 47.

In making the sucker rod of the present invention, the cable 48 may be placed in the rod mold and stretched taunt. For this purpose, the cable must be of a substantially longer length than the finished rod so that its ends may be placed in suitable tensioning apparatus. The rod 40 is then molded about the cable 48 with the cable lying on the rods longitudinal axis. In the embodiment of FIGURE 2, the recesses 50 may be formed in the molding step or as a separate step. The formation of these recesses would probably be more economically done during the casting operation.

After the molding step, the ends of the cable are cut off to form the end 52 which, in the embodiment of FIGURE 3 is essentially flush with the end of the rod, and in the first discussed embodiment extends into the recesses but not beyond the ends of the rod. In the first discussed embodiment, the cable ends 52 are then splayed so that the strands of the cable are separated from each other and extend randomly within the recesses 50. Molten metal is then poured into the recesses and allowed to harden about the splayed strands of the cable ends. Any suitable metal may be used such as Babbitt metal. Due to the fact that the cable strands are randomly disbursed within this hardened metal, a very secure bond will be formed for the cable ends at each end of the pipe.

As can be seen from the foregoing, the objectives stated at the outset have been achieved. An improved sucker rod has been disclosed which decreases the possibility of breakage by making the rod lighter; and should such a break occur in the rod, provides means whereby the portion of the pumping apparatus below the break can be easily and quickly recovered from the well without the necessity of a fishing operation. A sucker rod has been disclosed which utilizes as an integral part of the rod a cable extending substantially the entire length of the rod. This cable is attached to the rod throughout its length and at both ends of the rod. Thus the cable will remain effective regardless of the point at which the rod breaks, with the exception of breakage at the point of connection of the rods.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for the purpose of disclosure, numerous changes in the details of construction, and the combination, shape, size and arrangement of parts may be restorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. In well pumping apparatus including,

a surface pumping unit, and

a downhole pump,

a sucker rod string connecting said surface pumping unit to said downhole pump for reciprocating said pump, said string being comprised of,

a plurality of sucker rods comprising,

substantially solid elongate fiber glass rods,

threaded connecting means at each end of said elongate rods, and

cables extending substantially the entire length of said elongate rods and substantially the entire length of said connecting means, said cables being connected to their respective elongate rods throughout the length of said cables,

each of said sucker rods being further defined as including,

recesses in opposite ends of the rod,

the ends of the cable extending into said recesses, and

securing means for securing the ends of the cable in said recesses.

2. The invention of claim 1, wherein said securing means are defined as,

each end of the cable being splayed within its recesses,

and

hardened metal substantially filling each recess, the splayed end of the cable being distributed throughout said hardened metal.

3. A sucker rod for use in a pumping well comprising,

a substantially solid elongate rod having,

thread means on opposite ends of the rod for attachment to other well pumping equipment,

a recess in each end of the rod,

a cable extending substantially the entire length of the rod and being connected to the rod throughout the length of the cable, the ends of the cable extending for a portion of the length of the thread means and into the recesses,

each end of the cable being splayed within its recess,

and

hardened metal substantially filling each recess, each splayed end being distributed within the hardened metal in its respective recess, whereby the cable ends are secured at the ends of the rod.

References Cited UNITED STATES PATENTS 851,118 4/1907 Chadwick 52727 1,756,205 4/1930 Merrick 52727 3,212,582 10/ 1965 Brown l66-242 3,406,443 10/ 1968 De Ridder 29-4743 JAMES A. LEPPINK, Primary Examiner US. Cl. X.R, 

